2,4-D, Cotton, and Sprayer Contamination

The three leading causes of 2,4-D injury are: volatilization (or vapor drift), spray drift, and sprayer contamination. The potential for injury from each of these causes can be greatly reduced by adhering to best management practices as described in the following paragraphs.

Sprayer Contamination The final way in which cotton injury can occur is from minute residues of 2,4-D (banvel or phenoxy herbicides) in a sprayer. It is recommended highly that any sprayer previously used to apply 2,4-D not be used in cotton. If such a sprayer must be used, it should be washed thoroughly before spraying cotton. Special attention should be given to sprayers used to apply emulsifiable concentrates because these products seem to be particularly effective at pulling 2,4-D residues out of a sprayer.

The following procedure is recommended for washing out sprayers that have been used to apply 2,4-D. Keep in mind that this procedure may not totally remove 2,4-D residues. Dispose of rinsates in an approved manner. Rinsates resulting from this product may be disposed of on-site or at an approved waste disposal facility.

  1. Remove nozzles, nozzle strainers, and in-line strainers. Using a soft brush, wash the nozzles and strainers with soapy water. Be sure to remove any visible deposits.
  2. Before replacing nozzles and strainers, fill sprayer tank (at least 1/4 full) with water and add a strong detergent such as 4 pounds of trisodium phosphate per 50 gallons of water or a commercial spray tank cleaner. Agitate for 15 minutes and then flush about one-fourth of the water-detergent mixture through the lines. Replace nozzles and strainers and flush remainder of water detergent mixture through the nozzles.
  3. Spray diesel fuel on the inside surfaces of the tank. Start the sprayer to fill the lines, and let the diesel fuel sit in the lines for several hours, preferably overnight. Then spray out the diesel fuel. (Note: this step is suggested only if the sprayer has previously been used to apply an ester formulation of 2,4-D.)
  4. Fill the tank (at least 1/4 full) with water and add household ammonia at the rate of 1 quart per 25 gallons of water. Agitate for 15 minutes, spray a few gallons of the mixture through the nozzles, and let the remainder sit in the tank and lines for several hours, preferably overnight. Then spray out the remainder of the ammonia-water mixture.
  5. Fill the tank (at least 1/4 full) with water and detergent. Agitate for several minutes and spray it out.
  6. Fill the tank (at least 1/4 full) with fresh water and spray it all through the nozzles.
Be careful not to introduce 2,4-D from other sources, such as using a 2,4-D measuring device to measure cotton pesticides.

If you have any questions regarding the use of products containing 2,4-D ester contact your local retailer or Cooperative Extension Service representative for assistance.

Stolen and adapted from: "Mr. Cotton Doesn't Like Miss Ester: A Practical Guide to Significantly Reducing 2,4-D Injury to Cotton" produced by the 2,4-D Ester Stewardship Program.

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